I'm not really a fan of pasta salad, but when I do make it I use vinaigrette ( homemade, just follow any recipe and add whatever herbs you like - or none at all. I mix olive oil with lemon juice, a little mustard, salt , pepper and maybe a pinch oregano and/or mint. ) pour the vinaigrette over the pasta when it's still warm to let it absorb it better.

For tuna salad I just mix tuna with mayo and add in some veg/pickles/onions ( no pasta). To lower calories/fat, you can mix with cottage cheese

I love a dressing made of yoghurt, a little mayo, lots of lemon zest, a little italian dressing, and a little sugar.

ETA: I forgot the celery! I need my crunch

This is exactly the dressing I use for my cole slaw, and similar to what I use for my broccoli salad. It is so yummy, and obviously you can customize how creamy you want it with the proportion of yogurt and mayo.

My tuna salad isn't worth mentioning it's so weird, but it's basically chopped celery, onion, sweet pickles, dill pickles and then black olives if I have them. There's probably about 3 times as much of this as there is tuna.

I make a fabulicious cole slaw. I bet the dressing would go nicely in tuna. You may need to adjust the quantities a bit, but here's what I do for a full batch of cole slaw:

Grate one apple. (I use a firm, fairly sweet variety like Pink Lady or Gala.)Grate one yellow onion. (Wash hands.) Put this, along with most of the juice they generate, into a bowl. (If you really loathe raw onion, nuke it for half a minute to a minute to take the edge off.) Stir them together. Add a huge blob of mayo. (Start with half a cup. You may need to add up to a cup, depending on how much onion and apple you use.) Add a generous dose of mustard (if you're using a squirt bottle, you'll have to do two full squeezes; if not, two generous teaspoons is a good starting point). Salt with abandon. Pepper happily. Add 2 T. of white sugar. Stir, stir, stir. Add about 2 T. of cider vinegar. Stir. If the dressing doesn't look at least a bit liquidy, add two more 2 T. vinegar. Stir stir stir. Add to your heap of cabbage.

Obviously, that's not tuna. For the tuna, you might want to mince your apples and onions for added texture. The secret is to mix everything but the tuna together and then add it to the tuna.

Chunky pasta and tuna canned in water, chopped celery, red and yellow pepper, green onion and blanched green beans. The dressing was mayonnaise with lime juice, cumin, paprika, salt and pepper, and a bit of granulated garlic - I think it was about 1/4 cup mayo to the juice of half a large lime, heavily seasoned. It came out very flavorful, with just enough dressing to bind things together, but not be goopy.

What I use in almost all my salads is: some oli, some (whine) vinegar, some lemon (or lime) juice, pepper and salt, that is it.

What my mother used to say is: wise with oil, sparesome (stingy?) with vinegar. So I splash the oil and drip the vinegar in the salad.

That reminds me of one of the quote about the men needed to make a salad: "a spendthrift for oil, a miser for vinegar, a counselor for salt, and a madman to mix it all up." I'm not sure who said it. Maybe it's just an old proverb.